The present invention relates to ultrasonic imaging. More particularly, it relates to an improved ultrasonic transducer for use in ultrasonic imaging systems.
In the art relating to ultrasonic imaging, especially in the field of medical diagnostics through ultrasonic imaging, there have been provided, both hand-held and mechanically supported transducer assemblies. These assemblies are held in juxtaposition with the body of the individual undergoing examination. Included in such transducer assemblies, in a piezoelectric ultrasonic transducer which alternately transmits ultrasonic pulses into the body under examination and receives reflected pulse energy from tissue interfaces within that body. These reflected pulses are translated into electrical signals. The electrical signals may then be converted into a graphic representation of the tissue interfaces from which the reflected pulses were received, thus constituting a non-invasive examination or diagnostic tool. In such transducer assemblies, especially the hand held variety, the transducer per se has heretofore been in the form of a single unitary transducer. In one known example of such apparatus, the transducer itself has been approximately one-half inch across a major face thereof. It has been found that such dimension is quite large relative to the wave length of the ultrasonic pulses transmitted and received by the transducer. Accordingly, reflective ultrasonic pulses received by the transducer at one part of the transducer may be totally out of phase with the impulse received from the same spot on the target at another part of the same transducer. This, in turn, results in the signals received at one part of the transducer neutralizing or summing to zero with signals received at other parts of the transducer. The obvious result of such neutralization is a reduced signal strength of the detected reflections.